Jointing machines including an adjustment roller, a support roller and a locking wheel are known in the art. A description of various modifications of such jointing machines is contained in the article "Verbinden von Blech durch Falzen", pp. 447-449 and 507-511 in the trade magazine "Fertigungstechnik" 3. Jg., Vols. 11 and 12, Nov. and Dec. 1953, East Berlin. A specific embodiment of such jointing machines is shown in FIG. 29a on page 508 of the above article. This specific embodiment, however, has the disadvantage of being suitable only for joining large relatively thin metal sheet segments, as it is very difficult for the described apparatus to handle thicker metal sheet segments.